The Americans with Disabilities Act (ADA) requires the removal of physical obstacles to those who are physically challenged. Included within the scope of the ADA are motor vehicles, such as trains and buses. Specifically, new, used, or remanufactured buses sold are required to comply with the applicable provisions of the statute. One such provision requires that deployed lift platforms, when occupied, shall have devices for preventing the lift platform from dropping an occupant in the event of a single failure of any load-carrying component. Therefore, to comply with the ADA, redundant support systems need to be included on passenger lifts.
Currently, there are a wide variety of passenger lifts available for motor vehicles. One such lift is adapted to be mounted within an entryway of a motor vehicle. Such a lift includes a vertical reciprocating lift platform assembly mounted within the vehicle, the lift platform selectively actuatable between at least a raised and a lowered position. The lift platform assembly consists of an inboard platform and an outboard platform. The outboard platform is hingedly attached to the outboard edge of the inboard platform by two sets of horizontally oriented pin assemblies. The pin assemblies are located on opposite sides of the lift platform assembly. The inboard edge of the inboard platform is hingedly attached to two vertical support members located in the entrance of the passenger vehicle by a second set of two horizontally oriented pin assemblies. The vertical members can be selectively raised and lowered to convey the attached lift platform assembly between the raised and lowered positions.
The pin assemblies allow the lift platform assembly to be rotatably transfigured from a stowed position to an extended position. In the extended position, the upper planar surface of the inboard platform is oriented parallel with and above the ground. The outboard platform is rotated on the pin assemblies outward from the inboard platform until the upper planar surface of the outboard platform is coplanar with the inboard platform. Once in the extended position as described, the lift platform assembly is lowered to the ground or sidewalk so that a mobility impaired individual may board the lift platform assembly. Two drive chains, one attached to the left vertical member, the other attached to the right vertical member, of a reciprocating assembly are actuated to raise the vertical support members and the attached lift platform assembly. Once in the raised position, the lift platform assembly is level with the floor of the motor vehicle. The mobility impaired person is then free to deboard the lift platform assembly into the passenger compartment of the vehicle.
The lift platform assembly is then rotatably transfigured into the stowed position. This is done by rotating the folding platform until the upper surface of the folding platform is parallel with and opposing the upper surface of the inboard platform. The inboard platform and outboard platform are further rotated as a unit into a vertical stowed position, nested between and parallel with the vertical support members. Although such a lift is effective at providing mobility impaired persons, such as those in a wheelchair, access into and out of a motor vehicle, it is not without its problems.
For instance, the drive chains of the reciprocating assembly are coupled to the frame of the lift platform by a single securing device. More specifically, in the above-described lift, each of the drive chains is attached to one of the vertical support members by a clevis. The devises are then adjustably attached to mounting brackets on the vertical support members. The devises have a threaded portion that mates with the mounting bracket through a set of adjusting nuts. By selectively engaging the adjusting nuts associated with either the left or right drive chain, a user can level the lift platform assembly. Although the described apparatus of attaching the drive chains to the vertical support members is advantageous since it allows the leveling of the lift platform assembly, it is not without problems. Specifically, if a catastrophic failure occurs in the clevis, or the lower portion of the mounting bracket, or if the threads of a clevis disengage from the mounting bracket adjusting nuts, or other such failure, the lift platform assembly could canter to one side, or drop, injuring the lift user or others in proximity to the lift.
Such a passenger lift is not only dangerous, it also fails to comply with the ADA regarding single point failure of any load carrying component. Further, such passenger lifts are also not in compliance with proposed rules recently submitted to the Department of Transportation (DOT) by the National Highway Traffic Safety Administration (NHTSA) for possible inclusion in the Federal Motor Vehicle Safety Standards (FMVSS) that if enacted, will establish even more stringent requirements with at least regard to the single point of failure provision.
For at least the foregoing reasons, there exists a need for a passenger lift that includes a redundant support in the event of a failure of a portion of the lift, wherein the redundant support complies with the ADA requirements and the proposed FMVSS changes, is economical to install and maintain, and may be easily retrofitted into existing passenger lifts.